'the binocular brightness of two component uniocular brightnesses, of such order of intensity as used in these experiments (and with the eye not adapted for dark [note: 'Piper, Zeits. f. Psych. u. Physiol. d. Sinnesorgan., XXXII. 161, 1903.']), seems to lie near the arithmetic mean of the two components' (43)

'The chief evidence for some slight low-level communication between the right and left eye-systems, elicited by my work, has been the slightly lower frequency of stimulation found necessary for flicker-extinction under 'alternate left-right ' excitation than under 'simultaneous.' The slight excess of brightness of the haploscopic over the uniocular image, recorded by so many observers, and shown by Piper [note: 'Zeits. f. Psychol. u. Physiologie. d. Sinnesorgane., XXXII. 161, July, 1903.'] to be much more considerable for the dark-adapted eye, may be taken as evidence in the same direction.' (58-59)